Hole structure and production method for hole structure

Abstract

The invention provides a hole structure through which is formed a deep through-hole having microscopic open ends, and also provides a method of fabricating the same. The hole structure of the invention contains a through-hole having a first open end and a second open end larger in size than the first open end, wherein the size, d, of the second open end is not smaller than 2 μm and not larger than 50 μm, and the through-hole has a depth t larger than d but not larger than 15d. The fabrication method of the invention comprises the steps of: forming an electrically conductive opaque layer in a prescribed pattern over a transparent substrate; forming a layer of insoluble photosensitive material on one side of the transparent substrate where the electrically conductive opaque layer is formed; applying exposure to the insoluble photosensitive material layer from the other side of the transparent substrate where the electrically conductive opaque layer is not formed; developing the insoluble photosensitive material and thereby forming a resist that matches the prescribed pattern; and forming the hole structure by electroplating on the one side where the resist has been formed.

1 . A method for fabricating a hole structure through which is formed a through-hole having a first open end and a second open end not smaller in size than said first open end, said method comprising the steps of: 
 forming an electrically conductive opaque layer in a prescribed pattern over a transparent substrate;    forming a layer of insoluble photosensitive material on one side of said transparent substrate where said electrically conductive opaque layer is formed;    applying exposure to said insoluble photosensitive material layer from the other side of said transparent substrate where said electrically conductive opaque layer is not formed;    developing said insoluble photosensitive material and thereby forming a resist that matches said prescribed pattern; and    forming said hole structure by electroplating on said one side where said resist has been formed.    
     
     
         2 . A hole structure fabrication method as claimed in  claim 1 , further comprising the step of removing said resist, said electrically conductive opaque layer, and said transparent substrate.  
     
     
         3 . A hole structure fabrication method as claimed in  claim 2 , wherein said hole structure contains at least one element selected from the group consisting of Ni, Cu, Co, Sn, Zn, Au, Pt, Ag, and Pb.  
     
     
         4 . A hole structure fabrication method as claimed in  claim 2 , wherein said exposure is applied by using ultraviolet radiation.  
     
     
         5 . A hole structure fabrication method as claimed in  claim 2 , wherein said through-hole has an interior shape corresponding to said resist.  
     
     
         6 . A hole structure fabrication method as claimed in  claim 1 , further comprising the steps of: 
 removing said resist;    forming a second layer of insoluble photosensitive material over said hole structure;    applying second exposure to said second insoluble photosensitive material layer from the other side of said transparent substrate where said electrically conductive opaque layer is not formed;    developing said second insoluble photosensitive material and thereby forming a second resist that matches said prescribed pattern;    forming a second hole structure by electroplating on said one side where said second resist has been formed; and    removing said second resist, said electrically conductive opaque layer, and said transparent substrate.    
     
     
         7 . A hole structure fabrication method as claimed in  claim 6 , wherein said second hole structure contains at least one element selected from the group consisting of Ni, Cu, Co, Sn, Zn, Au, Pt, Ag, and Pb.  
     
     
         8 . A hole structure fabrication method as claimed in  claim 6 , wherein said exposure or said second exposure is applied by using ultraviolet radiation.  
     
     
         9 . A hole structure fabrication method as claimed in  claim 6 , wherein said hole structure and said second hole structure are bonded together.  
     
     
         10 . A hole structure fabrication method as claimed in  claim 6 , wherein said through-hole has a first interior shape corresponding to said resist and a second interior shape corresponding to said second resist.  
     
     
         11 . A hole structure fabrication method as claimed in  claim 10 , wherein said first interior shape and said second interior shape are substantially equal in size.  
     
     
         12 . A hole structure fabrication method as claimed in  claim 10 , wherein said first interior shape is larger in size than said second interior shape.  
     
     
         13 . A hole structure fabrication method as claimed in  claim 6 , further comprising the step of forming a second electrically conductive layer between said hole structure and said second insoluble photosensitive material.  
     
     
         14 . A hole structure through which is opened a through-hole having a first open end and a second open end not smaller in size than said first open end, wherein 
 said hole structure is formed by back exposure and electroforming processes,    said through-hole has an interior shape corresponding to the shape of said resist,    the size, d, of said second open end is not smaller than 2 μm and not larger than 50 μm, and    said through-hole has a depth t larger than d but not larger than 15d.    
     
     
         15 . A hole structure as claimed in  claim 14 , wherein 
 said back exposure and electroforming processes comprise the steps of: 
 forming an electrically conductive opaque layer in a prescribed pattern over a transparent substrate;  
 forming a layer of insoluble photosensitive material on one side of said transparent substrate where said electrically conductive opaque layer is formed;  
 applying exposure to said insoluble photosensitive material layer from the other side of said transparent substrate where said electrically conductive opaque layer is not formed;  
 developing said insoluble photosensitive material and thereby forming a resist that matches said prescribed pattern; and  
 applying electroplating on said one side where said resist has been formed.  
   
     
     
         16 . A hole structure as claimed in  claim 15 , wherein when the area of said first open end is denoted by s 1  and the area of said second open end by s 2 , s 2 /s 1  is not smaller than 1 and not larger than 9.  
     
     
         17 . A hole structure as claimed in  claim 16 , wherein when the angle that an inner wall of said through-hole makes with a centerline of said through-hole is denoted by θ, θ is not smaller than 0° and not larger than 12°.  
     
     
         18 . A hole structure as claimed in  claim 16 , wherein said depth t is not smaller than 1.5d and not larger than 5d.  
     
     
         19 . A hole structure as claimed in  claim 16 , wherein said hole structure has a plurality of through-holes formed at a pitch b which is not larger than 2t.  
     
     
         20 . A hole structure as claimed in  claim 16 , wherein said first or said second open end is circular or elliptical in shape.  
     
     
         21 . A hole structure as claimed in  claim 16 , wherein said first or said second open end is polygonal in shape.  
     
     
         22 . A hole structure as claimed in  claim 15 , wherein when the angle that an inner wall of said through-hole makes with a centerline of said through-hole is denoted by θ, θ is not smaller than 0° and not larger than 12°.  
     
     
         23 . A hole structure as claimed in  claim 22 , wherein when the area of said first open end is denoted by s 1  and the area of said second open end by s 2 , s 2 /s 1  is not smaller than 1 and not larger than 9.  
     
     
         24 . A hole structure as claimed in  claim 22 , wherein said depth t is not smaller than 1.5d and not larger than 5d.  
     
     
         25 . A hole structure as claimed in  claim 22 , wherein said hole structure has a plurality of through-holes formed at a pitch b which is not larger than 2t.  
     
     
         26 . A hole structure as claimed in  claim 22 , wherein said first or said second open end is circular or elliptical in shape.  
     
     
         27 . A hole structure as claimed in  claim 22 , wherein said first or said second open end is polygonal in shape.  
     
     
         28 . A hole structure through which is formed a through-hole having a first open end and a second open end not smaller in size than said first open end, wherein 
 the size, d, of said second open end is not smaller than 2 μm and not larger than 50 μm, and    said through-hole has a depth t larger than d but not larger than 15d.    
     
     
         29 . A hole structure as claimed in  claim 28 , wherein when the area of said first open end is denoted by s 1  and the area of said second open end by s 2 , s 2 /s 1  is not smaller than 1 and not larger than 9.  
     
     
         30 . A hole structure as claimed in  claim 29 , wherein when the angle that an inner wall of said through-hole makes with a centerline of said through-hole is denoted by θ, θ is not smaller than 0° and not larger than 12°.  
     
     
         31 . A hole structure as claimed in  claim 29 , wherein said depth t is not smaller than 1.5d and not larger than 5d.  
     
     
         32 . A hole structure as claimed in  claim 29 , wherein said hole structure has a plurality of through-holes formed at a pitch b which is not larger than 2t.  
     
     
         33 . A hole structure as claimed in  claim 29 , wherein said first or said second open end is circular or elliptical in shape.  
     
     
         34 . A hole structure as claimed in  claim 29 , wherein said first or said second open end is polygonal in shape.  
     
     
         35 . A hole structure as claimed in  claim 28 , wherein when the angle that an inner wall of said through-hole makes with a centerline of said through-hole is denoted by θ, θ is not smaller than 0° and not larger than 12°.  
     
     
         36 . A hole structure as claimed in  claim 35 , wherein when area of said first open end is denoted by s 1  and area of said second open end by s 2 , s 2 /s 1  is not smaller than 1 and not larger than 9.  
     
     
         37 . A hole structure as claimed in  claim 35 , wherein said depth t is not smaller than 1.5d and not larger than 5d.  
     
     
         38 . A hole structure as claimed in  claim 35 , wherein said hole structure has a plurality of through-holes formed at a pitch b which is not larger than 2t.  
     
     
         39 . A hole structure as claimed in  claim 35 , wherein said first or said second open end is circular or elliptical in shape.  
     
     
         40 . A hole structure as claimed in  claim 35 , wherein said first or said second open end is polygonal in shape.